tracing: Do not let synth_events block other dyn_event systems during create

[ Upstream commit 4f67cca70c0f615e9cfe6ac42244f3416ec60877 ]

synth_events is returning -EINVAL if the dyn_event create command does
not contain ' \t'. This prevents other systems from getting called back.
synth_events needs to return -ECANCELED in these cases when the command
is not targeting the synth_event system.

Link: https://lore.kernel.org/linux-trace-devel/20210930223821.11025-1-beaub@linux.microsoft.com
Fixes: c9e759b1e8456 ("tracing: Rework synthetic event command parsing")
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c
index 22db3ce95e74f2fffa774656d43204692605b0ae..8c26092db8dee54d60088a0c80be36eb3dc0143f 100644 (file)
--- a/kernel/trace/trace_events_synth.c
+++ b/kernel/trace/trace_events_synth.c
@@ -2053,6 +2053,13 @@ static int create_synth_event(const char *raw_command)
 
        last_cmd_set(raw_command);
 
+       name = raw_command;
+
+       /* Don't try to process if not our system */
+       if (name[0] != 's' || name[1] != ':')
+               return -ECANCELED;
+       name += 2;
+
        p = strpbrk(raw_command, " \t");
        if (!p) {
                synth_err(SYNTH_ERR_INVALID_CMD, 0);
@@ -2061,12 +2068,6 @@ static int create_synth_event(const char *raw_command)
 
        fields = skip_spaces(p);
 
-       name = raw_command;
-
-       if (name[0] != 's' || name[1] != ':')
-               return -ECANCELED;
-       name += 2;
-
        /* This interface accepts group name prefix */
        if (strchr(name, '/')) {
                len = str_has_prefix(name, SYNTH_SYSTEM "/");